Rockwool and spray foam accomplish the same thing- both will help deaden the sound waves, but they will still transmit through solid members i.e. wood joists, strapping, wall plates. Air gaps and multiple staggered layers of decoupled sheetrock (resilient channel and sound clips create air space between layers and eliminate hard connections) are probably the way to go- and likely what a sound engineer would spec. You’re looking at $30k easy. And probably wouldn’t be happy with the results. Getting new neighbors would be more effective